Catalyst-free photoinduced radical sulfonylation/cyclization of unactivated alkenes toward sulfone-containing quinazolinones

Abstract

The difunctionalization of alkenes based on the insertion of sulfur dioxide has been considered to be one of the most straightforward and powerful strategies for the construction of sulfones. Numerous strategies for activated alkenes have been developed in this area. However, progress in the SO₂ insertion-mediated difunctionalization of unactivated alkenes, which encounters higher reactivity and shorter survival times of the alkyl radical intermediate, remains elusive and unresolved. Here, we report a strategy to access sulfonated quinazolinones from readily accessible aryl diazonium salts and Na₂S₂O₅via a catalyst-free photocatalytic system. The process is proposed to involve a photoinduced sulfur dioxide insertion/sulfonyl radical addition to an unactivated CC double bond/Minisci-type cyclization sequence. This approach features high functional group tolerance, broad substrate scope, and synthetic simplicity, and thus offers opportunities to rapidly build up sulfone-containing quinazolinones.